ML20006E139
| ML20006E139 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 02/06/1990 |
| From: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML113202353 | List: |
| References | |
| 50-263-89-29, EA-89-248, NUDOCS 9002220146 | |
| Download: ML20006E139 (2) | |
Text
7 NOTICE OF VIOLATION Northern States Power Company Docket No.
50-263 Monticello Nuclear Generating Plant License No.
OPR-22 EA 89-248 During an inspectian conducted on October 13 through November 27, 1989, a e
violation of NRC requirements was identified.
In accordance with the " General i
Statement of Policy and Procedure for NRC Enforcement Actions," 10 CFR Part 2, Appendix C (1989), the particular violation is set forth below:
10 CFR Part 50, Appendix B, Criterion XI, Test Control, requires, in part, that a test program be established to assure that all testing required to demonstrate that structures, systems, and components will perform satisfactorily in service, is identified and performed in accordance with written test procedures which incorporate the requirements and acceptance limits contained in applicable design documents.
Technical Specification Limiting Condition for Operation (LCO) 3.7.C.)
requires secondary containment integrity to be maintained during all modes of plant operation unless specific exemption criteria are met.
In addition, Technical Specification Surveillance Requirement 4.7.C.I.c requires secondary containment capability to maintain at least a 1/4 inch of water vacuum under calm wina conditions with a filter train flow rate of not more than 4,000 sefm.
This shall be demonstrated at each refueling outage prior to refueling.
Contrary to the above, from June 1971 until October 1989, the licensee failed to establish an adequate surveillance test to demonstrate that secondary containment was capable of maintaining 1/4 inch of water vacuum under calm wind conditions with a filter flow rate of not more than 4,000 scfm. The l
surveillance test was inadequate in that interaction with other ventilation systems was not properly considered.
This is a Severity Level III violation (Supplement I).
Pursuant to the provisions of 10 CFR 2.201, Northern States Power Company
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(licensee) is hereby required to submit a written statement or explanation to the U.S. Nuclear Regulatory Commission, ATTN:
Document Control Desk, Washington, D.C. 20555, with a copy to the Regional Administrator, Region III, U.S. Nuclear Regulatory Commission, 799 Roosevelt Road, Glen Ellyn, Illinois 60137 and a copy to the NRC Resident Inspector at the Monticello Nuclear Generating Plant, within 30 days of the date of the letter transmitting this Notice. This reply should be clearly marked as a " Reply to a Notice of Violation" and should include:
(1) admission or denial of the alleged violation; (2) the reasons for the viola-
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tion if admitted; (3) the corrective steps that have been taken and the results achieved; (4) the corrective steps that will be taken to avoid further viola-tions; and (5) the date when full compliance will be achieved. Where good cause is shown, consideration will be given to extending the response time.
If an 9002220146 900206 DR ADOCK 0500 3
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I-Notice of Violation 2
i adequate reply is not received within the time specified in this Notice, an order may be issued.to show cause why the license should not be modified, i
I suspended, or revoked or why such other action as may be proper should not be taken.
i FORTHENUCLEARREGULATORYCOMSISSION ti
$hadw Y.)]<h.kw "DC, Bert Davis Regional Administrator i
Dated at Glen Ellyn, Illinois this 6th day of February 1990 l'
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W.5 kUCLEAR RtGUtATORY COMMI5510N
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klGION !!!
. Report No. 50263/8902p(DRP)
Docket No.- 50 263 License No. OPA-22 Licensee: Northern States Power Compary 414 Nicollet Mall Minntepolis, MN 55401 Facility Name: Monticello Nuclear Generating Station Inspection Att Monticello 5tte, Monticello, Minnesota Inspection Conducted: October 13 through November 27,19C9 1
Inspectors:
J. E. Hard 1
I P. 8. Moore I I
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Approved By:
W. L.Yx
.12 L /89 Reactor Projects Branch 2 Date l
_ Inspection Sumary insoection on October 13 through Noyember 27,1989iReportNo. 50 263/89029(DRP))
Areas espectos: : specie 1 unannounces ins >ection by sne relisent inspectors or seconsory containment integrity and stand >y gas treatment system issues.
l Results: The inspection revealed that the licensee took tenediate corrective j
action to investigate the secondary containment issue, stopping work in
- progress which depended on secondary containment integri
. Correcties action was teken presqpt1. However, the surveillance procedure or the standby ges 0
treatment system
$875) ens not adequate, so degraded secondary containment inteer ty any have existed for-en eatended period of-time. - One akparent L
- violat en was Identified for not meeting the seconda containmen foto technical specification because of inadequate survell ance procedures. grity L
(rareiraph r.a.).
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Persons Contacted
'D. Antorgy, General Superintendent Engineering 8 Red. Prot.
Plant Manager
- 8. D. Day, M. H. ClarityI, Assistant to the Plant Manager General Superintendent Operations D. E. NevinskGeneral Superintendent, Maintenance W. J. Hill R. L. ScheInost, General Superintendent Quality, Security 8 Admin.
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A. E. Ward le$pperintendsnt ' Operations Engineering
- 5. J. Naamer l
ad Product'.on ingineer D. A. Scotl, Senior Production Engineer 1
S. K. Peterson, production Engineer l
Other plant personnel were also contacted by the inspectors.
- In attendance at the exit seeting.
2.
Followup of Events
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f a.
Event Sumary i
On October 13 3g89, discussions between RRC personnel and the l
General Superintendent, Engineering and Radiation Protection were held to review the results of Standby Gas Treatment system ($$7$)
testing at the Duane Arnold Energy Center. (Duane Arnold personnel 4
found a breach in their secondary containment which was detected during$GTStesting.) Based on this discussion, Monticello management I
ordered tunediate cessation of control red scree testing, which was in progress at the tism until these questions on $675 testing and secondary containment in,tegrity could be answered. A special test of the SGTS with the reactor building plenum exhaust fans secured was conducted on October 34 and was witnessed by the resident inspection staff.
(see further discussion of the design features in peregraph 2.b. below.) This test showed that the16T8 by itself was not capable of paintaining a reactor building vaceus of et least 0.25 The vacuum developed by SSTS durins the test was 0.1 inch inch of water as spec fled in Technical $pecification (f$
4.7.C.).
The licensee made the required notifications to the NRC within four hours as specified in 10 CFR 60,72 and h Licensee Event Report (LER) 263/89029 withi.130 days.
Major efforts were undertaken by the licensee to sessure the 'as-found*
condition of the secondary containment from which hpothetical post-accident doses could be cosputed, and to deterstne and correct the sources of in-leakage 'to the reactor building. Leekage from the reactor butiding into the reactor buildin exhaust plenum was determined to be about 2600 cfm with the longa exhaust fans and the
$$t$ operating. This is the amount of at flew through dampers which o
bypassed the $GTS wnder these conditions. Lestage into the reactor l
building was shown to be principally through six sets of ventilation t
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b dampers which did met close properly end through the reactor building
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railwsy str1ock door pasket material. Following gasket repiecesent a retest with only $4T$ operating showed and repair of the dampers, lop a reactor building vacuum of 0.3 inch J
that the system would deve of water, we11 within the required 0.25 toch specified in T5.
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Deshn Backgewnd
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Secondary contairment at Monticello is provided by the reactor i
building. The SGT5 is provided to exhaust the reactor butiding atmosphere to the offges stack via a filter system when it is necessary to 40 so. This arrangement is designed to limit ground l
1evel releeses of radioactive materials in the event of accidental releases inside the reactor building.. Each of two trains of $615 4
is required to maintain the reactor building at 0.25 inch of water vacuum with respect to atmospheric, under calm wind conditions.
i This ensures that even with significant wind, en the order of 40 mph, enfiltration from the reactor building will be limited.
i Normal reactor building ventilation air exhausts to a reactor 3
building plenum which is a large room attached to the reactor l
building but outside the secondary contairment boundary. This plenum contains a variety of fans including three plenum ekhaust fans plus other ventilation equipment.
The plenum enhaust fans are only provided with normai power and I
cannot be operated under loss of-offsite-power ennditions. When normal power is available, two of these fans tvn continuously, discharging to the reactor building vent, and maintaintag the plenum t
room at a vacuum of 0.5 inch of water relative to staespheric, Since the $6TS develops less than 0.5 inch of w ter vacuum in the reactor butiding (actually measured at 0.3 inch it follows that openings between reactor building and plenum wi I result in air flow toward the plenum even with $6TS operating. This flow of reactor building air which is not filtered, as is $6TS flow,'and which.is' discharged out the reactor building vent rather than the effgas' stack is referredD as ' bypass flow.' As noted above the as-found bypass flow was asaspred et 2600 cfm.
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Event tvaluation t
Since plant startup. Monticello has tested the $$T$ with the reactor building plenum exhaust fans operating. Therefore, the true 9erformance of $8TS and the condition of secondary containment may inve been masked during this entire time. On October 14, when $6TS was tested without the plenum exhaust fans operating, inadequate vacuum (0.1 inch) was drawn indicating excessive leakage into the reactor building and proving that this masking has Men taking place.
- The licensee also sensured the as found bypass flow (8600 efts on which offsite dose calev1stions were based. Discussten of the various dose calculations performed by General tiectric Co. for the licensee follows.
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Dose caleviations were performed for the two design basis accidents i
for which trofit for $6T5 is assused in the USAtt the Less of Coolant Accident (LOCA) and the Refueling Accident (REFA). Further, i
U$AR and for the source term from Re u1 story Guide 1.3 (R.S.1.
each accident dose was computed for the source tem discussed in An additional breakdown was made so oses could be computed assuming that bypass flow.was present and also asswning that 56T5 and secondary contairment did not exist. This gave a total of eight different cases for whict doses were computed.
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For these accidents the calculations showed that using the USAR source ters assumptions, doses at the tuclusion Area Soundary, in l
the Low population tone and to the control r all would be within regulatory guide ines. However, using R.
1.3 source ters assumptions, the inhalation doses at all three locations would be l
excessive for the LOCA as would the Exclusion Area Soundary inhalation dose for the REFA.
Further celtv14tions were made to estimate how long after en accident i
the plenum exhaust fans could be left running without exceeding regulatory dose guidelines assuming the more restrictive source ters from R.S.1.3 and 2600 cfm bypass flow. These calculations by l
General Electric showed that the fans could remain runnin for at least 45 minutes following a LOCA. (Calculations for REF are underway. No fuel movements will be wraitted until t are i
complete.) lased on these results, tTe licenset decide that manual actions to turn off the plenum exhaust fans after a LOCA were an ll acceptable short-term fix to the question. A method was developed.
tested, and procedura11 ed to accomplish this.
e.
Corrective Actions (See LER 263/89029) h sumery of Corrective Actions Taken:
lI (1) All work requiring secondary containment integrity was stopped immediately open identification of the concern.
l4 (t) 'The Secondary Containment capability Test was changed to require securing the Reactor Sv11 ding Plenum tahavst Fans during the test.
(3) All Secondary Containment isolation dampers were inspected; six sets of dampers were repaired.
(4) Access plates were installed in ventilation ducts to permit s
inspection of damper vanes.
(5) The threshold weatherstrip gasket material for Reactor Building I
ta11way Airlock doors was replaced.
(6) After 411-inspections and repairs were completed, the revised Secondary Containment Capability Test was performed satisfactorily.
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(7) Operatins procedures cere revised to requien tripping the Reactor Building plenum tuhaust Fans eithin 45 minutes of any event that requires init16 tion of Standby Gas Treatment System for radioactive releases from within secondary containment.
j Sumery of Corrective Actions to be Taken:
i (1) Corrective maintenance testing procedures will be standardised to assure that secondary containment isolation dampers are fully functional. procedures will be prepared, reviewed and approved by March 1, 1990.
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(t) preventive maintenance procedures will be written to require inspection of material condition of secondary containment 1 solation dampers and to require corrective maintenance as degradation is discovered. procedures will be prepared, reviewed and approved by December 31,1990.
(3) Preventive maintenance procedures w111 be written to require inspection of the material condition of secondary containment l
atriock doors and to require corrective maintenance es degradation is discovered. Procedures will be prepared, i
reviewed and approved by December 31,1990, (4) Design changes are being considered to improve the Reactor-Building to Reactor lui ding plenum boundary integrity and t
to reduce bypass flow during secondary containment isolation conditions. This review will be complete by Decee6er 31,1990.
L (5) All Technical Specification required surveillance tests will be reviewed to ensure that performance of Safety Related equipment is not being enhanced by the operation of Non-Safety Related equipment. Tests will be reviewed by June 1,1990.
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. (6) The design basis of secondary containment and Standby Gas 4
Treatment systhms will be reviewed as part of the licensee'r.
configuration management p ram on an sapedited basis. This review will be completed b cember 1990.
3.
Init Interview The inspectors met with D. Antony, plant kanager. on November 27,1989, to discuss the scope and findings of the inspection.
In addition, the inspector also discussed the likely informational content of the inspection report with regard to documents or processes reviewed by the inspector during the inspection. The licensee did not identify any such documents or processes as proprietary.
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